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I installed a new dryer in our house. It runs but won't heat. It has a 240V 3 wire connection. There is a 30 amp double pole breaker installed in the breaker box. (the box is very old) I've read that you should get 120V from each leg to the neutral which I do. I also read that you should get 240V across the two. Only a few volts register on the meter, not 240. How is this possible and what changes should I make to correct this?

  • Where are you taking the measurement at the breaker box, or at the receptacle? – Tester101 May 7 '11 at 14:09
  • Please measure the voltage at the breaker and let us know what you get. Who installed the breaker? Has it been successfully used before? – Philip Ngai Apr 25 '12 at 22:04
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Is it possible that both poles are connected to the same phase (e.g., if your house only has 120-volt service)?

  • I was taking the measurement at the recepticle. There are a couple other 2 pole breakers and I'm pretty sure that the oven is 240V. Could a section of the breaker box be only 120V and another 240V. This is an old breaker box so I'm not sure. – Jon May 7 '11 at 16:28
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You have one of these.

enter image description here src

It's not a 2-pole breaker. It's a twin, duplex, tandem, cheater or double-stuff breaker giving two 120V circuits in a single space in the panel, intended to be used for 120V circuits when you have run out of space in the panel. That doesn't work as discussed here. One space can only access 120V.

You need a 2-pole breaker.

If you have run out of space in the panel, they make 240V 2-pole double-stuffs; they take 2 spaces, contain 4 breakers, with the middle two tied together providing your 240V circuit. They are available with or without the outer tie. These are not simply handle-tied; there is also an internal mechanism doing the tying. Hence you cannot simply add ties to 120V breakers, unless the manufacturer says you can.

enter image description here

  • Lol I have seen this several times in the past + . I even have a few tandem 30's on the shelf great answer with the pics @Harper + – Ed Beal Mar 16 '17 at 22:30
  • Don't forget GE makes a double pole tandem. (Takes up one normal space but actually uses both ungrounded legs/phases). – Kris Mar 16 '17 at 23:28
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Look at the vertical location of your double pole breaker. The first 2 slots in a column are on one phase, the next two are on the other phase. A double pole breaker has to have one connection to each phase, so it has to start on an even location. Look at the breaker for the stove, your dryer needs to be an even number of locations away from it.

  • 2
    This is incorrect: every other position is a different phase. A 240V breaker always spans two phases, it doesn't matter where it is. – gregmac May 11 '11 at 1:27

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